The manufacture of reverse loop sliver knit fabric using a circular sliver knitting machine for producing a pile fabric is well known in the art. Typically, a doffer roll is used to receive the sliver fiber from a card unit. Needles mounted on a rotatable cylinder receive the sliver fibers from a doffer roll as hooks on the needles enter the fillet wire of the doffer roll and draws sliver fibers after the needles have risen to a clearing level along a predetermined wave-like path. The hooks of the needle also pick up a yarn which is used to anchor or secure the sliver fibers such that free ends of the sliver fibers project from one side of the fabric. Examples of this approach to knitting pile fabric may be seen in U.S. Pat. Nos. 3,299,672 and 3,710,597 to Schmidt.
Schaab et al. in U.S. Pat. Nos. 4,244,198 and 4,245,487 and Kuhrau et al. in U.S. Pat. No. 5,431,029 which have been assigned to the applicant of the present invention each disclose a method and apparatus for making reverse loop sliver knit fabric which is a significant departure from the traditional manufacturing techniques described above. The traditional manufacturing method reverse loop sliver knit fabric resulting in a single knitting of the sliver fibers into the base fabric. This results in a pile fabric which is both long and has an uneven length. It is therefore necessary to finish the product by shearing the pile to the desired height and napping or brushing the sheared pile to minimize any flaws in the fabric.
Schaab et al. and Kuhrau et al. knit the sliver fabric into a typical J-loop or U-loop on the first pass of the needles in accordance with the previously described techniques. However, unlike previous methods, Schaab, et al. and Kuhrau et al. each use an air nozzle which is positioned radially inward from the needles and sinkers. The purpose of the air nozzle is to turn the free ends of the sliver, previously knitted into the base fabric during the first pass of the needles, over the sinkers so that the remaining free ends, assuming that they are of sufficient length, will be knitted a second time or interlaced into the fabric. The result is that the length of the free ends remaining after the second pass is shortened and as a consequence, the pile will be shorter, therefore, less waste will occur as result of shearing.
In addition to using a circular sliver knitting machine to knit reverse loop sliver fabric, it is common to knit fabric having a high or deep pile. Examples of such uses of a circular sliver knitting machine may be seen in U.S. Pat. Nos. 3,728,872 to Thore, 4,050,267 to Schaab et al., and 4,187,700 to Koegel. Typically, a circular sliver knitting machine which is used to manufacture high pile fabric uses air nozzle units located radially outward of the needles so as to blow air radially inward (see for example U.S. Pat. No. 4,187,700 to Koegel and Italian Patent No. 710,949).
Unfortunately, the arrangement of the air nozzle units on a circular sliver knitting machine used to manufacture a reverse loop sliver fabric typically are located radially inward from the needles so as to blow air radially outward (see for example U.S. Pat. Nos. 4,244,198 and 4,245,487 to Schaab et al. and U.S. Pat. No. 5,431,029 Kuhrau et al.). As a result, considerable down time and modification of the machine is necessary to convert the machine redirect the air flow and relocate the air nozzle units so as enable the circular sliver knitting machine to knit conventional high or deep pile fabric. The difficulty, cost and down time associated with attempting to convert such a machine makes such conversions impractical. As a consequence, many knitting companies will be limited to knitting sliver into either high pile fabric or reverse loop fabric, thereby limiting themselves from as much as one half of the potential market. Alternatively, a knitting company will be required to buy two different machines which are each dedicated to a different type of sliver knitting.
If this alternative is chosen, depending on the production requirements of the end customer, up to as many as one half of the expensive circular sliver knitting machines cannot be used and remain idle. Furthermore, the ability to only knit either reverse loop fabric or high pile fabric on a particular circular sliver knitting machine, necessarily limits the number or variety of patterns which may be achieved by the machine.